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"Are DUI checkpoints legal? If I get arrested at a DUI checkpoint, can I get my case thrown out?"

During the “Drinko” de Mayo weekend earlier this month, you may have seen the roadway signs, flashing police lights, and uniformed officers across L.A. County diverting drivers into a conveyer-belt line to check for drunken driving.

These visually choreographed sobriety checkpoints usually pop up around different cities, including Glendora, West Covina, and Monrovia, at popular holidays or any given weekend. And despite your annoyance with the lines of cars and police questioning, or even anger with the feeling that your Constitutional rights were harmed (the Fourth Amendment provides “[t]he right of the people to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”), these checkpoints are legal.

In 1990, the United States Supreme Court in Michigan Dep’t. of State Police et al. v. Sitz et al.[1] held that, given the known gravity of drunk driving on the public safety, properly conducted sobriety checkpoints did not run afoul of the Constitution, even as innocent people are necessarily stopped—or seized—without reasonable suspicion of committing a crime. The Court concluded: “In sum, the balance of the State’s interest in preventing drunken driving, the extent to which this system can reasonably be said to advance that interest, and the degree of intrusion upon individual motorists who are briefly stopped, weighs in favor of the state program. We therefore hold that it is consistent with the Fourth Amendment.”[2]

Years earlier in 1987, the California State Supreme Court in a case called Ingersoll v. Palmer[3] had already upheld the validity of law enforcement sobriety checkpoints. These stops were valid as long as they followed the “strict guidelines” established by the court and were carried out in a manner consistent with both the state and federal Constitutions.

The “strict guidelines” in Ingersoll require:

1. Decision making at the supervisory level: This means that the decision of the nature, scope and purpose of the sobriety checkpoint are made and established by supervisory law enforcement personnel, and not by an officer in the field.[4] This requirement is important to reduce the potential for arbitrary and capricious enforcement.[5]

2. Limits on discretion of field officers: Selection of which drivers ought to be stopped must be based on a neutral formula, such as every driver or every third driver, etc. As the Ingersoll Court observed, “To permit an officer to determine to stop any particular driver or car when there is no legitimate basis for the determination would be to sanction the kind of unconstrained and standard-less discretion which the United States Supreme Court sought to circumscribe in its decisions . . . .”

3. Maintenance of safety conditions: The checkpoint should only be conducted when traffic volume allows for safe and effective inspections.[6]

4. Reasonable location: Sites ought to be chosen to maximize the government interest in preventing drunk-driving harms to the public safety.[7]

5. Time and duration: Law enforcement will be expected to exercise good judgment in setting the time and duration of these checkpoints. The goal is to minimize intrusiveness and maximize effectiveness.[8]

6. Indicia of official nature of roadblock: The flashing lights, patrol cars, signs and uniformed officers serve to minimize the intrusiveness of the checkpoint, according to Ingersoll, increase safety, and alert drivers that this is a legitimately authorized stop.[9]

7. Length and nature of detention: Since the traffic stop is considered a seizure under the Fourth Amendment, the Ingersoll Court stated that these stops should not last any longer than what is reasonably necessary to discern whether a person is intoxicated. According to the court:

Minimizing the average time each motorist is detained is critical both to reducing the intrusiveness of the stop on the individual driver and to maintaining safety by avoiding traffic tie-ups. [E]ach motorist stopped should be detained only long enough for the officer to question the driver briefly and to look for signs of intoxication, such as alcohol on the breath, slurred speech, and glassy or bloodshot eyes. If the driver does not display signs of impairment, he or she should be permitted to drive on without further delay. If the officer does observe symptoms of impairment, the driver may be directed to a separate area for a roadside sobriety test. At that point, further investigation would of course be based on probable cause.[10]

8. Advance publicity: The Ingersoll Court found that the publicity requirement, such as a notice in the local paper, served to reduce the intrusiveness of the expected law enforcement stop and increased deterrence among would-be drunk drivers.[11]

Now, that it is established that these sobriety checkpoints are legal, what happens if you get busted for a DUI. Can you get your case thrown out?

The answer to this question lies in the specific circumstances surrounding your arrest; in other words, the facts of your case, but, in general, the expert DUI defense attorneys at Coimbra Law will devise a strategy to attack the evidence against you. Among the possibilities:

Question the procedure:

Was the law enforcement stop “proper”? Did it follow the “strict guidelines” established by the California State Supreme Court? For example, were you randomly selected for the stop based on a neutral standard? Was your detention within a reasonable amount of time?

Question the integrity of the results:

If the officer suspects that you have been drinking based on signs of slurred speech, odor, glassy eyes or other attributes, you will be directed away from the checkpoint line for further investigation. At that point, you may be asked to perform a Field Sobriety Test and or be asked to take a breath test.

Unfortunately, even if you are sober, a field test could lead an officer to falsely believe you were intoxicated. These tests are far from scientific and there are many environmental and other factors which could affect the results. A few of these factors can include the weather, the surface you are standing on, roadside turbulence, your shoes or clothing, and any physical, physiological, medical, and mental, disability or condition you may have.

Our DUI defense attorneys in Glendora, West Covina, and Monrovia are meticulous in looking at these factors. We have investigators who can go out to the scene and investigate the site of your DUI arrest and Field Sobriety Test to determine if there are any grounds to challenge the evidence against you.

The breath tests are similarly open to scrutiny.

During a DUI investigation, police customarily administer two kinds of breath tests: the breathalyzer test (or the PAS - preliminary alcohol screening test), which can be done on site. Another test, the evidentiary test uses a desktop breathalyzer and can be completed at a sobriety checkpoint or police station after an arrest. The first of these two tests, the breathalyzer test, is elective, meaning that you can chose to take either a blood test or another breath test. If the officer suspects you of drug use, you will be required to take the blood test. Moreover, if you refuse to take a chemical test after you have been arrested, your license will be suspended for a minimum of one year and you will receive enhanced penalties if you are ultimately convicted of a DUI in court.

These breath tests must be administered very carefully in order to avoid false reads or any type of errors. Unfortunately, police are not always as careful or properly trained in administering these tests. California DUI breath tests are vulnerable errors, and can be challenged.

The DUI defense attorneys in Glendora, West Covina, and Monrovia have experience successfully challenging a number of DUI arrests, including those resulting from law enforcement checkpoints.

· The police MUST adhere to protocol in carrying out the DUI breath testing:

· Law enforcement personnel are required to calibrate breath testing devices every 10 days or every 150 uses, whichever happens comes first.

· They can only use DUI breath testing devices approved in California.

· Routine calibration and testing of these instruments is required.

· There must be adequate training of personnel who administer the DUI breath test.

· There must be a continuous 15-minute observation period prior to commencement of the test (during which time you must not drink, eat, smoke, or vomit).

· The operator must secure 2 separate DUI breath test results which vary by no more than 0.02 grams per 100 milliliters of blood alcohol.

They must keep a proper record at each phase of instrument calibration, the DUI arrest and the DUI breath test.


[1] Michigan Dep’t. of State Police et al. v. Sitz et al., 496 U.S. 444 (1990)

[2] Michigan Dep’t. of State Police et al. v. Sitz et al., 496 U.S. 444 at 455

[3] Ingersoll v. Palmer, 743 P.2d 1299 (1987)

[4] Ingersoll v. Palmer, 743 P.2d 1299 at 1342

[5] U.S. v. Martinez-Fuerte, 428 U.S. 543 (1976)

[6] Ingersoll v. Palmer, 743 P.2d 1299 at 1342-43

[7] Ingersoll v. Palmer, 743 P.2d 1299 at 1343

[8] Ingersoll v. Palmer, 743 P.2d 1299 at 1345

[9] Ingersoll v. Palmer, 743 P.2d 1299 at 1345

[10] Ingersoll v. Palmer, 743 P.2d 1299 at 1346

[11] Ingersoll v. Palmer, 743 P.2d 1299 at 1346-47